Introduction to Semi-Supervised Learning  (English, Electronic book text, Zhu Xiaojin)

The single most striking feature: self-contained. Almost no prior knowledge is required, except a good background in probability. The style of presentation is clear and concise.

The mathematical rigour is just right. There is no hand-waving, neither vague language. Some sections do tend to get detailed and terse - but this is unavoidable given the state-of-the-art of the field and the small size of the book

Highly recommended. Would have given 5 stars, if there were a cheaper edition